Yeah, I agree with you that you can get joy out of old material possessions such as your car, I do so myself. But I wonder if you're applying the Stoic philosophy in the correct way?

I also read a part of the book so when you say you try to think "I really like this car", shouldn't the thought be "Boy imagine I'd lose this car today, or maybe it gets robbed, I better enjoy it before that happens" instead? At least that's what I got out of the book, to excercise "negative visualization regularly.